Servicing of refrigeration or air conditioning systems providing less than satisfactory performance usually involves a check-out of the refrigeration side of the system. This entails obtaining pressure measurements on both the high pressure and low pressure or suction side of the compressor. Service connectors to which a pressure gauge can be connected are commonly provided for this purpose in the refrigerant tubing by the fabricator of the system or alternatively are improvised by the serviceman on site. The procured pressure measurements enable a diagnostic analysis of system performance while identifying deficiencies in the system that can be readily remedied for improving system operation to manufacturer's standards.